1. Field
This invention relates generally to receivers, and more specifically, to combining different signal paths and reusing a SAW-less receiver circuit with a SAW receiver operation on a same pin.
2. Background
In a full duplex, frequency division duplex (FD-FDD) system, the receiver and transmitter operate simultaneously on different frequencies, which provide the necessary separation between uplink and downlink signal paths. However, current radio frequency (RF) front-end (FE) design for an FDD long-term evolution (LTE) and carrier aggregation (CA) transceiver is very complex. For example, each band of the full duplex systems such as Wideband Code Division Multiple Access (WCDMA) require receive/transmit (Rx/Tx) surface acoustic wave (SAW) filters or duplexers to avoid being jammed by the transmit power leakage into the receiver. In half-duplex systems such as Global System for Mobile communications (GSM) Time Division Synchronous CDMA (TDS-CDMA), and Time Division Long-Term Evolution (TD-LTE), an Rx SAW filter is required to avoid being jammed or de-sensed by out-of-band blockers as high as 0 dBm. Thus, in half-duplex systems, several techniques are employed to substantially reduce the need for the Rx SAW filter due to the absence of a concurrent operation of the transmitter. However, the removal of the Rx SAW filter causes the out-of-band (OOB) jammers with high input level to be present at the input of the low noise amplifier (LNA).